I'm playing with Mapr Sandbox and i don't understand what is the role of Mapr Warden application. The Mapr website contains references to configuration files, but there is no description of the program itself.
2 Answers
1
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Warden is a light Java application that runs on all the nodes in a cluster and coordinates cluster services. Warden’s job on each node is to start, stop, or restart the appropriate services, and allocate the correct amount of memory to them. Warden makes extensive use of the znode abstraction discussed in the ZooKeeper section of this Guide to monitor the state of cluster services.
Warden configuration is contained in the warden.conf file, which lists service triplets in the form ::. The number of nodes element of this triplet controls the number of concurrent instances of the service that can run on the cluster. Some services, such as the JobTracker, are restricted to one running instance per cluster, while others, such as the FileServer, can run on every node. The Warden monitors changes to its configuration file in real time.
For more, See Cluster Management, subsection for warden
1
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Warden is a daemon that runs on all the cluster nodes to manage and monitor the other services running in a cluster node. It's like a watchdog. The warden will not start any services unless Zookeeper is reachable and more than half of the configured Zookeeper nodes are alive.
Check this link https://www.mapr.com/blog/mapr-cli-101-tutorial#.VQKob_mUe3I
